Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

The levels of ACTH change with the body's natural 24-hour cycle of processes (circadian rhythms). This test is most accurate if it is performed early in the morning.

How to prepare for the test:

The health care provider may advise you to stop taking steroid drugs. You may need to be at the laboratory or office where the blood is being drawn by or before 8 a.m.

How the test will feel:

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed:

This test can help find the causes of hormone problems.

The main function of ACTH is to regulate the steroid hormone cortisol, which is released by the adrenal cortex.

Normal Values:

Normal values: 9 - 52 pg/mL

Note: pg/mL = picograms per milliliter

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.